1. Field of the Invention
The present invention generally relates to an integrated device electronics (IDE) control device and, more particularly, to an IDE control device suitable for any clock frequency specification, which is characterized in that an IDE controller comprises a phase-locked loop and a selection module so as to generate and select clock signals suitable for various hard discs such that the data transmission rate is enhanced.
2. Description of the Prior Art
In recent years, with the high development in information-related industries, people have increasing needs for a higher operation speed as well as a higher data transmission rate of information products. In view of this, the industries have made lots of efforts and continuously proposed various specifications for new products. For example, various specifications for hard discs such as ATA (advanced technology attachment), ATA33, ATA66, ATA100 and ATA133 have been disclosed. The data transmission rate of a hard disc increases whenever a new specification is proposed.
Even though most of the new specifications can be used for the old products, they may, however, adversely affect the performance. Please refer to FIG. 1, which is a block diagram of the conventional IDE control device. As shown in the figure, the main control chip 14 (for example, a south bridge chip) comprises an IDE controller 16 that is connected to and controls a first hard disc 18 and a second hard disc 19 through an IDE bus 17. Furthermore, a clock signal generator 12 is included to generate clock signals, by which the IDE controller 16 generates a transmission signal. The generated clock signals may vary in frequency according to various specifications for the motherboard, for example, 100 MHz for PC100 and 133 MHz for PC133. More particularly, for PC100, even though the frequency of the clock signal is 100 MHz, an ATA133 hard disc with higher data transmission rate cannot bring its performance into full play. On the contrary, a PC133 motherboard providing an external clock frequency of 133 MHz can perfectly match an ATA133 hard disc to achieve an enhanced data transmission rate. However, when a PC133 motherboard is used together with an ATA100 hard disc that transmits a word in 17 to 20 ns (equivalently, 2 clock cycles for PC100), it can only achieve the performance of a clock frequency of 89 MHz since it takes 3 clock cycles (where each clock cycle for PC133 is 7.5 ns) to transmit a word.
Therefore, there is need in providing an IDE control device suitable for any clock frequency specification in view of the above problems such that various products with different specifications can be compatible.